A top U.S. official on refugees recently visited Vietnam's central highlands and concluded that ethnic minority Montagnards who were repatriated to Vietnam last year have not been harassed by authorities. But groups such as Human Rights Watch are skeptical about the claims, as Matt Steinglass reports from Hanoi.

Up to 2,000 members of ethnic minority groups living in Vietnam's central highlands, known as Montagnards, have been back in their home villages since late 2005. They had participated in violent protests in Easter 2004, then fled to Cambodia.

Later, under an agreement between Cambodia and Vietnam arranged by the United Nations, the Montagnards were sent back to Vietnam - some against their will. Although Hanoi pledged not to persecute them, rights groups feared for their safety.

Last week, Ellen Sauerbrey, the U.S. undersecretary of state for population, refugees and migration, visited those villages with Hanoi's approval.

"We were allowed to meet with, time permitting, about seven returnees, and have private conversations with them, without government officials being present. And I have to report that, with no exceptions, the people who were returned from Cambodia that we spoke with all indicated that there has been no punishment," Sauerbrey says.

Human Rights Watch has reported that Montagnards who participated in the 2004 demonstrations were beaten and imprisoned, and that some of those sent back from Cambodia were persecuted. The group's Asia director, Brad Adams, finds Sauerbrey's comments hard to accept.

"We have spoken to returnees who have been threatened, harassed, and beaten, in Vietnam, after returning from Cambodia," Sauerbrey says.

He also discounts Sauerbrey's report that the Montagnards she spoke to could not recall why they had fled Vietnam, and that they probably had left for economic rather than political reasons.

Adams says Sauerbrey did not speak to enough people to get an accurate picture.

Foreign observers are rarely allowed into the highlands to investigate allegations of rights abuse. Many of those allegations come from anti-Communist émigrant groups in the U.S. and France.

The Vietnamese government describes such accusations as propaganda.

Sauerbrey says the only way to prove Vietnam's statements that none of the Montagnards have been mistreated is for the government to allow more access to the highlands.

"The best way for those activists is to see for themselves. And that means the best thing that the government of Vietnam can do is keep opening the doors," Sauerbrey said.

On this point, Human Rights Watch's Adams agrees.

"If no one is being mistreated, throw the whole place open to outside observers. All the time," Adams said.

The term Montagnards covers several ethnic groups in Vietnam's central highlands, and experts say historically many of those groups faced discrimination and poverty. More recently, the government has increased economic aid to highland minority groups.

Many Montagnards also are members of evangelical christian churches. While some of these churches have recently been approved by the government, others are still considered illegal.

Some Montagnard groups sided with South Vietnam and the United States in the Vietnam War, and tens of thousands fled to the U.S. or Europe after the war.